Low density parity check (LDPC) codes using low density parity check matrices in which the density of “1” is low are known. When error correction in a soft decision scheme is performed for decoding LDPC codes, high correction ability can be achieved but the processing time is increased. When error correction in a hard decision scheme is performed, on the other hand, the processing speed can be made higher but there is a problem that sufficient correction ability cannot be achieved.
Thus, in related art, a technique of combining the hard decision scheme and the soft decision scheme in such a manner that errors that cannot be corrected in the hard decision scheme are corrected in the soft decision scheme is known.
When the hard decision scheme and the soft decision scheme are combined, however, there is a problem that the configuration for packaging using semiconductor integrated circuits or the like becomes complicated.